Allthings is a webapp that makes it easier to organise your to-dos, add files and links you may need to refer to, and work with other people when you need to.
The video above gives you an idea of what the service can do. It's free for individual users, and it's come a long way since I started testing it a few months ago. It's great if you're just looking for a feature-rich to-do app that's more than a blind checklist. AllThings allows you to upload files, create dependent tasks, and set up multiple lists and workspaces for different projects and parts of your life.
AllThings also makes it easy to collaborate with other users, or share your entire to-do list or checklist with anyone who needs to see it. This can be especially useful if you're working on a list of ideas, for example, and want to send the whole list to your boss to see what they think of them in one go. You'll need to pony up some cash for a premium subscription if you want to get other people in your collaboration group. Even so, the free account will work for most people, and if you're working on a small team, the £2.49 (~$4.50) per user/per month charge may be more attractive than other premium services with similar feature-sets. Hit the link below to check it out.